DVD movies are guarded by a CSS (content scrambling system) encryption code, a security developed and used by Hollywood as a defense against movie piracy. In simple terms, CSS encrypts data on the DVD with a special key able to unscramble it. The key is not a secret to DVD playing software developers who need it to read the information on the software.

CSS protection uses a 40-bit encryption. In simple terms, copies cannot be played, as the key will be missing. The key is not writable on DVD-RW or DVD-R discs. The Digital Millennium Copyright Act guarded against the distribution of illegal players, with the intention of eradicating the menace of copying. Therefore, it would seem there is no such thing as a DVD copy.

However, the protection proved incompetent. The CSS encryption code was cracked, which subsequently spawned a number of other DVD copying software. CSS protection apart, Macrovision has come up with their form of protection against copying that can also be found on VHS tapes. However, advances like this are not always universally applied, so there are some compatibility issues cropping up.

There are several software programs that can successfully decode the CSS encryption. One is the DVD decrypter that not only removes the protection, but also gives the user the luxury of ripping specific portions off the movie. Plus, it can copy them to a DVD recordable.

AnyDVD is another software application that can remove the protection. Unlike the DVD decrypter, AnyDVD allows the user to rip and burn directly.